Preparation of high molecular weight alcohols



Jan. 14, 195s 2,820,067

PREPARATION OF HIGH MOLECULAR WEIGHT ALCOHOLS v.1. K.MERTzwEn Lr.-:RET'AL Filed DeO. 30, 1953 EMHSS twig? .mQOmQ Qvx .nam soonmrow Qmml ZMJOJoseph K. Merfzweller Neville L. Cul! Inventors Edward A. McCracken By 6JJ 27H06 Afrorney United States Patent-f() PREPARATION F HIGH MOLECULARWEIGHT ALCOHGLS Joseph K. Mertzweller, Baton Rouge, Neville L. Cull,Baker, and Edward A. McCracken, Baton Rouge, La., assignors to EssoResearch and Engineering Company, a corporation of Delaware ApplicationDecember 30, 1953, Serial No. 401,234

9 Claims. (Cl. 260-638) The present invention relates to the preparationof oxygenated organic compounds from olefins by reacting the latter withCO and H2 in the presence of carbonylation catalysts. More specifically,the present invention relates to the preparation of high molecularweight alcohols from low molecular weight olens by a novel modificationof the aldehyde synthesis, or carbonylation reaction.

The synthesis of primary alcohols from olefins by treating the latterwith CO and H2 in the presence of a carbonylation or hydroformylationcatalyst, particularly cobalt, is well known in the art. In the firststage the olefinic material, catalyst and H2 and CO are reacted atelevated pressures and temperatures to give a product consistingessentially of aldehydes containing one more carbon atom than the olen.This mixture, which contains dissolved in it salts and carbonyls of thecatalyst, is treated in a second stage to cause removal of the metalcompounds from the aldehyde product. Thereafter, the catalyst-freealdehyde product is generally hydrogenated to the corresponding alcohol,having in turn one more carbon atom than the olefin from which it isderived.

This carbonylation reaction provides a particularly attractive methodfor preparing valuable primary alcohols which find large marketsparticularly as intermediates for plasticizers, detergents, solvents andlubricants. Amenable to the reaction, to a greater or less extent, aremost organic compounds having olenic unsaturation, such as olenichydrocarbons, oxygenated compounds, and olefin polymers.

The catalyst in the first stage may be added as the olefin-soluble saltof cobalt, such as cobalt oleate' or naphthenate. Also, aqueoussolutions of cobalt compounds, or slurries of oil-insoluble forms ofcobalt may be 'employed. Inasmuch as the active catalyst is probablycobalt hydrocarbonyl, most forms and compounds of the element may beemployed, for they are converted into the active catalyst in the courseof the reaction.

The synthesis gas mixture fed to the first stage may consist of an Hz/COratio of 4 to l to l to 4, preferably l/l. Reaction conditions in thefirst, or aldehyde synthesis stage, vary somewhat with the nature of theolefin feed and form of catalyst; generally the reaction is conducted atabout 200G-4500 p. s. i. g., preferably 2500- 3500 p. s. i. g. and at atemperature of about Z50-375 F.

Following the carbonylation stage the aldehyde product, containing insolution considerable amounts of dissolved catalyst, is generallytreated at elevated temperatures in the presence of a gas or vapor, suchas H3 or steam, or preferably liquid water, to decompose the carbonyl toan oil-insoluble form of cobalt, and thereafter the aldehyde product,freed of suspended catalyst, is hydrogenated to alcohol in the presenceof conventional hydrcgenation catalyst.

Useful as this process is for the preparation of alcohols, the techniqueis subject to several limitations which severely affect its utility forcertain purposes. First and foremost is the fact that, though thereaction is rapid and rice yields are high with relatively low molecularoleins, the reaction rates and yields drop rapidly as the molecularweight increases.l Though this elect is noticeable even in straightchain olefins, it becomes particularly pronounced when it is desired tocarbonylate highly branch chained molecules, such as those formed byacid polymerizing of low molecular Weight oleins. Thus the yield of C16alcohol prepared by subjecting a C15 propylene polymerizate to thecarbonylation reaction is substantially smaller than that obtained bycarbonylating the C12 fraction, which in turn is smaller than the C9,etc. The monomer carbonylates extremely rapidly. This follows fromsteric considerations.

A second limitation of the carbonylation process for the production ofhigh molecular weight alcohol lies `in the unavailability of sufficientquantities of feed stocks. Again, when propylene is polymerized withitself and with butylenes under conventional acid polymerizationconditions, the yields of polymer drop off rapidly after reaching a peakwith the C9 olefin, i. e., the propylene trimer and with increasingmolecular weight, the polymer yields become too small to afford acommercially feasible operation for preparing higher molecular weightalcohols, suchas C16 and higher. Olefins may also be prepared by suchprocesses as wax cracking, but this is a costly process and theproducts, being straight chained, do not lend themselves to uses where amore branched material is desirable.

It is, therefore, the principal purpose of the present invention to setforth a process for producing primary alcohols in relatively highmolecular weight in good yields by the alcohol synthesis, or Oxoreaction.

It is also a purpose of the present invention to prepare, by amodification of the carbonylation reaction, good yields of alcohols fromolens which are readily available in commercial amounts.

A still further object of the present invention is to set forth a novelprocess for converting aldehydes to alcohols of higher molecular weight.

v Other and further objects and purposes of the present invention willbecome more clear and apparent hereinafter.

It has now been found that when the aldehyde product produced in thefirst stage of the carbonylation process istreated at low 4pressureswith certain salts and compounds of fzinc, at elevated temperatures foran extended period of time there is obtained, after hydrogenation, highyields of a primary alcohol product having 2n-1-2 carbon atoms when anolefin having n carbon atoms is passed to the carbonylation stage. Thus,when a C9 olefin is converted to the aldehyde and the latter treated inaccordance with the invention, a C20 primary saturated alcohol productis recovered in good yields. C19 olefms are a rarity, and it is readilyapparent that by this process readily available oletin feeds such asheptene, nonene, and dodecylene, may be converted to high molecularweight alcohols which are not available from high molecular weightolefins.I `The best results are obtained when Zinc metal or zinccompounds are employed. High yields of both the monomeric and dimericalcohols are recovered. In contrast to those processes wherein aldehydesarel treated with aldolizing agents, no significant amounts of glycolsare produced.

In accordance with the present invention, the first stage aldehydeproduct, preferably prior to decobalting, is mixed with 0.05-5 weightpercent of a salt or compound of zinc. The salt may be dissolved inwater, hydrocarbon, or oxygenated products. After mixing, the mixturecontaining the dimerization catalyst is passed to a soaking and settlingvessel in which temperatures are maintained in the range of about 200 to450v F.pressures 2,820,067 I Patented Jan. 14, 1958 of atm. to 100G p.s. i. g., and holding times of 2-48 hours. lf desired, the soakingvessel may be packed with mossy metal or metal turnings,` such` as zinc,in which case the mixing equipment may be eliminated.-

An important advantage of this process is the fact that the cobaltcatalyst is removed and recovered more readily. Also, as will be shownbelow,` the reaction modiiier is more active in the presence ofdissolved cobalt carbonyl than when it is added to aldehydes from whichcobalt has been removed by prior decobalting. The heat soaking greatlydepletes the cobalt content of the aldehyde and a cobalt-rich aqueousphase can be removed from the soaker, if an aqueous solution 'of thereaction modifier is employed. The small amount of residual cobaltcatalyst may then be removed in conventional decobalting equipment, butof much smaller capacity than hitherto necessary.

The present invention and its application will best be understood fromthe more detailed description hereinafter, wherein reference will be hadto the accompanying drawing, which is a schematic representation of asystem suitable for carrying out a preferred embodiment of theinvention.

Referring now to the drawing, an olefin, preferably one having less thanl5 carbon atoms, is passed through line 2 to the bottom of primaryreactor 4. Suitable catalyst, such as cobalt oleate, may be dissolvedtherein to the extent of (Ll-0.5% by weight, based on cobalt. Reactor 4is a high pressure vessel which is preferably packed with non-catalyticmaterial, such as ceramic rings and is preferably divided into discretezones` separated by support grids.

A stream of synthesis gas comprising H2 and CO is passed into reactor 4via line 6. Reaction conditions in the carbonylation zone comprise`temperatures preferably in the range of about SOO-375 F. and pressuresof about 2500-3500 p. s. i. g., and a normal residence time of 1-3hours.

Liquid aldehyde product, as well as secondary reaction products,containing catalyst and gases in solution are withdrawn upwardly throughline 8 and passed through cooler 10 to high pressure gas-liquidseparator 12 where unreacted gases are withdrawn overhead through line14 for recycle. Liquid carbonylation product, the aldehyde content ofwhich contains essentially one more carbon atom than ,the olefin feedadmitted through line 2 and which liquid product contains in solutionappreciable concentrations of cobalt compounds', such as thehydrocarbonyl, is withdrawn fromseparator 12 via line 16. A portion ofthis stream is recycled to reactor 4 via line 18, cooler 20 and line 22,to aidin cooling and maintenance of temperature control of the primarycarbonylation stage. A

The balance of the primary reaction product not recycled to reactor 2 iswithdrawn through pressure release valve 24 and passed via line 26 tomixer 28.- To the mixer there is supplied, through line 30, a solutionof zinc salt, either aqueous, hydrocarbon` or oxygenated solvent beingoperable. About`0.05i5% by weightof zinc salt, such as zinc acetate, maybe employed. A fter mixing, the material is passed to a combinationsoaking and settling vessel 34 via line 32. `Within 34 a tiem peratureof about 200 to 450 F. and pressures of about atm. to 1000 p. s. i. g.are maintained. Soaking tirne at these conditions may be from about 2 toabout 48 hours.

In the modification wherein an aqueous dimerizing agent is used, anaqueous stream is withdrawn downwardly from soaker 34 through line 36.This stream, containing both zinc and cobalt, may be recyced or used asmake-up. l y I The reaction product, now containing substantialquantities of both the monomeric and dimer'ic aldehyde V and alcoholproduct, and still .containing soute cobalt @mounds is Passed. fo, e.e'sdb'af fesl @arbeids the mixture is treated with hot water oi'- steamor vapor to decompose and remove inorganic materials, includingcompounds of cobalt and zinc. Because of the pretreatment at soakingconditions, equipment smaller than conventional may be employed.

The decobalted material is thereafter passed to a hydrogenation zone(not shown) where, under conventional hydrogenation conditions and knowncatalyst, conversion of aldehydes to alcohols is completed, and theresulting products, consisting essentially of the alcohol having n+1 andthe alcohol having 2n+2 carbon atoms resulting from an olefin having ncarbon atoms, are distilled and recovered.

The process ofthe present invention may be subject to manymodifications, without departing from its spirit. Thus, aldehydes fromlother sources than those derived from the carbonylation reaction may betreated in accordance with the invention, though the latter has itshighest utility when the aldehyde is treated in theppresence ofdissolved cobalt carbonyl. Also, it may be desirable to add at least aportion of the reaction modier directly to the first, or carbonylationstage. In that case, the etiiuent is thermally treated in accordancewith the present invention, with or without further addition of reactionmodifier. Though the reaction modifier is effective when added to thisstage, the normal residence time in a continuous operation is not alwayssuicient to give the highest yield of the dimer alcohol.

The invention may be further illustrated with the following specificexamples.

Exampe l Au octyl aldehyde product of 90% purity prepared by oxonating aheptene fraction and dstilling the aldehyde was treated with zinc atelevated temperatures under con- These data clearly show the high yieldsof higher boiling ralcohols to be obtained in accordance with theprocess of the invention.

Example II This example points up the beneficial results obtainable whenthe heat-treating and soaking step is included, but the reactionmodifier itself is added directly to the aldehyde synthesis reactor. Inthe example below, zinc acetate (0.2%) was added to and was presentduring the oxonation reaction with heptene. Products were withdrawn atatmospheric pressure from the oxonation reactor and heat-soaked instainless steel pressure bottles. The products after soaking Vweregreatly depleted in cobalt content, and small amounts of residualcatalyst removed by extracting with aqueous acetic acid. 'I'he productwas then hydrogenated in autoclaves over nickel catalyst, and C3 andCi.,v alcohols removed by distillation.

Example III A study was made of the effect of heat so'aki'ltigfluffy,oxo the yetdof arnaud with zinc' sans in an' enerf te iirereas dimeralcohol. The best results indicate that at about 01% Zinc lonconcentration, heat soaking the oro prot uct for l2 hours at 400 F. orwith 0.2% zinc at 300 F., gave about 16 wt. percent C15 alcohol. Ingeneral, temperatures higher than 400 F. and zinc concentrations inexcess of 0.2 wt. percent tend to favor high bottoms yields. Heatsoaking the undecobalted oxo product shows a denite advantage over heatsoaking decobalted oxo product with respect to amount of C16 alcoholformed. These data are shown in the following tables:

The product from the oxo reactor before decobalting was heat soaked withZinc salts under conditions indicated as follows:

A B C D E (l) (l) (l) (l) (l) 0. 1 0. 1 0. 1 0. 2 None (2) (2) (2) (2)(2) 300 400 500 300 300 Nitrogen pressure, p. s. i. v 500 500 500 500500 Time heat treated, hoursm.. 12 12 12 12 12 Wt. percent principalproducts: 3

Hydrocarbon 16.1 16. 5 16. 7 17. 8 14. 4 Ca alcohol 54. 9 51. 6 45. 248. 4 81. 0 Intermediate Cut. 7. 2 2. 7 13. 5 5. 5 6. 4 C1@ alcohol 9. 615. 7 5. 8 15. 9 8. 0 Bottoms 12. 2 13. 5 19. 4 13. 9 10. 2

l Zinc oleate. 2 Undecobalted oxo product.

3 Based on distillation ol heat treated oxo product hydrogenated inautoclave over reduced nickel catalyst. Carbonyl numbers on the feedindicate about 42% C8 aldehyde so that a wt. percent yield of C16alcohol of 16% is very good. Data indicate optimum yield:

(1) At 0.1% Zn and 400 F. (2) At 0.2% Zn and 300 F.

Temperatures of 500 F. are too severe and result in (l) Increased bottomyields.

(2) Increased intermediate cut yields-indicative of esters.

It will be noted that although heat soaking the oxo feed prior todecobalting results in some production of C16 alcohol, it is only halfof the yield obtainable with added zinc salts.

Exampe IV Decobalted oxo product was heat soaked with zinc salts underthe conditions indicated below:

Run No F G H Catalyst (l) (l) (1) Wt. percent z1nc 0. 2 0.5 0. 0

eed (2) (2) (2) Temperature, F-.. 350 350 350 Nitrogen, p. s. i. g 500500 500 Time heat treated, hours 12 12 12 Wt. percent principal productsa Hydrocarbon 14. 4 12. 5 12. 2 C; alcohol 53. 7 47. 9 72. 6Intermediate cut 5. 7 5. 5 4. 5 C15 alcohol 10. 6 12. 5 2. 9 Bottoms 15.1 21. 7 8.1

l Zinc oleate. 2 Decobalted oxo product.

l Based on distillation o heat treated oxo product hydrogenated inautoclave over reduced nickel catalyst.

It will be noted that heat treating the decobalted product with zincoloate resulto to on moreno lo 0 alcohol yield from 3% to l1-l2%. ltwill also be noted that this increase is not as great as was obtained onheat treating the oxo product before decobalting.

It will be noted also that in Examples III and IV the feed used was oxoproduct taken from a commercial oxo unit. Use of this feed per sewithout any further processing such as distillation, for example,constitutes a deflnite economic advantage over use of pure aldehydes.

What is claimed is:

1. In a process wherein olens having n carbon atoms in the molecule areconverted to an oxygenated reaction product comprising aldehydes byreaction with hydrogen, carbon monoxide and a cobalt carbonylationcatalyst at elevated temperatures and pressures, and said reactionproduct converted to an alcoholic product, the improvement whichcomprises heating said oxygenated reaction product with a zinccomprising material for 2 to 48 hours at a temperature of from about 200450 F., hydrogenating said treated product, and recovering a productcomprising monohydric primary alcohols having 2n-l-2 carbon atoms.

2. The process of claim 1 wherein said material is added to saidoxygenated reaction product prior to removal of cobalt carbonyltherefrom.

3. The process of claim 1 wherein said material is added to the extent0.05-5% by weight of aldehyde.

4. In a process wherein oletins having n carbon atoms in the moleculeare converted to an oxygenated reaction product comprising aldehydes byreaction with H2, CO, and a. cobalt catalyst at elevated temperaturesand pressures in an oxonation zone, and said oxygenated reaction productcontaining cobalt carbonyl in solution thereafter freed of cobalt andconverted to an alcohol product, the improvement of producing highyields of an alcohol product containing 2n-l-2 carbon atoms whichcomprises subjecting said oxygenated reaction product to a thermaltreatment in a soaking zone for 2-48 hours at 20G-450 F. in the presenceof from 0.05-5% of a zinc comprising material.

5. The process of claim 4 wherein said material is to said oxonationzone.

6. The process of claim 4 wherein said material is added to said soakingzone.

7. The process of claim 4 wherein said thermal treatment is carried outprior to removal of cobalt carbonyl from said oxygenated reactionproduct.

8. The process of claim 4 wherein said material is a zinc salt.

9. The process of claim 8 wherein said salt is zinc acetate.

OTHER REFERENCES Wender et al.: Bureau of Mines Report of Investigations4270, June 1948, pp. 1, 4 to 6, 9, l0 and l1.

Karrer: Organic Chemistry, Elsevier, N. Y., 1950; pp. 164, 170.

1. IN A PROCESS WHEREIN OLEFINS HAVING N CARBON ATOMS IN THE MOLECULE ARE CONVERTED TO AN OXYGENATED REACTION PRODUCT COMPRISING ALDEHYDES BY REACTION WITH HYDROGEN, CARBON MONOXIDE AND A COBALT CARBONYLATION CATALYST AT ELEVATED TEMPERATURES AND PRESSURES, AND SAID REACTION PRODUCT CONVERTED TO AN ALCOHOLIC PRODUCT, THE IMPROVEMENT WHICH COMPRISES HEATING SAID OXYGENATED REACTION PRODUCT WITH A ZINC COMPRISING MATERIAL FOR 2 TO 48 HOURS AT A TEMPERATURE OF FROM ABOUT 200*-450*F., HYDROGENATING SAID TREATED PRODUCT, AND RECOVERING A PRODUCT COMPRISING MONOHYDRIC PRIMARY ALCOHOLS HAVING 2N+2 CARBON ATOMS. 